Relay arrangement for use with voice-operated devices



March 31, 1931. I 1. HERMAN RELAY ARRANGEMENT FOR vUSE WITH VOICE OPERATED DEVICES Filed oct.

Patented Maf. 31, 1931 UNITED sTArEs PATENT Vol-rlc'sis JOSEPH HERMAN, OF WESTFIELD, NEW JERSEY, ASSIGNOR T0 AMERICAN TELEPHONE .AND TELEGRAPH COMPANY, A CORPORATION 0F NEW YORK RELAY ARRANGEMENT FOR USE WTI-I VOICE-OPERATED :DEVICESl Application filed etober 28, `19%. SerialNo. 144,848.

l'Ihis invention relates to improvements in relay arrangements, .and more `particularly to relay arrangements suitable for controlling voice `operated devices in signaling systems, such, for example, .as echo Suppressors or voice operated repeaters.

yVoice operated devices of the prior art have .usually depended on the feature of the quick operation of a relay when the voice currents arrive and upon .a definite hang-over time in the release fof this relay after the voice currents have ceased. lOne of the arrangements heretofore utilized for accomplishing these vtwo results depended upon the operaf tion of one or more slow-release relays by the voice operated relay, in which case a sacrifice is made as regards quick operation due to the tandem operation of relays. In another arrangement, .a combination of .two or more voicesoperated relays with several slow-release relaysy is made to act simultaneously upon the circuit to be controlled. In such cases complicated interlocking features are necessary which materially increase the possibillity of maintenance troubles.

'One of .the novel features of the arrangements of this invention consists in the method employed to :secure the-so-called hang-over time ofthe echosuppressing relay in the case of echo VSuppressors or 4the switching relay in the case .of voice operated repeaters when voice currents cease, without affecting a'dversely the time of operation of this relay when the voice currents begin. This is yaccomplishd by combining a slow electrical circuit with the usual vacuum tube detector circuit in which the relay windings are included. As .a result, a relay, which has its windings connected into the combined circuits, will operate quickly 'and yrelease slowly,

the time of releasing being determined largely -by the constants of the slow electrical cir.- cuit. Other features and purposes ofthe rinvention will appear more fully from the detailed description thereof hereinafter given.

'The' invention may be more fully understood from the following description, together with the accompanying drawing, in which is' shown :a :circuit diagram illustrating the invention as .applied to a four-wire echo suppressor. The showing of the invention as incorporated in a four-wire echo :suppressor is for purposes of illustration only andthe invention 'is not thus limited in Hits application.

In the arrangements of the invention illustrat-ed in the drawing as incorporated in a four-wire echo suppressor, the two functions of quick operation and slow release are iaccomplished by two relays. Both of these relays are `operated simultaneously upon kthe arrival of the voice currents, but only one of onlyin case the control relay remains released for a period of time which isslightly greater than the hang-over period.

A detailed description of the operation lof the arrangements is as follows: assume that a speaker is talking over the circuit L1 from west to east. The voi-ce currents will then pass through the amplifier A1 tothe distant listener. transformer T which is connected --to the line Part of this current reaches the Y at the output `of the amplifier A1 andfis then applied to the vacuum tube detector V. The

resulting plate current in the output ofthe vacuum tube operates the .two relays lgand 2 by flowing through the windings WV, and VS, respectively. The windings W2 and W4 are biasing windings which are supplied with current from the battery B,L and which are necessary in the case of polar relays. inthe case of the utilization of neutral relays, however, these windings wouldnot be used since the biasing action might then ybe performed the relay armatures.

The operation of the .two relays has the by means of .retractive .springs fastened toV y aou eration of the second half of the echo suppressor. The control relay l discharges the condenser Cl through the resistance R1 Vto ground and increases the operating current of the line relay. The increased operating current is due to the circuit which is established from the plate battery B2 through the relay winding VS, resistances R2 and R1, armature and M contact of the control relay to ground, and has no other elfect than to hold the armature of relay 2 more firmly on its M contact.

If the speaker stops talking, the plate current of the detector will fall to Zero and the control relay l will release under the influence of the biasing current in winding W72. The line relay 2, however, will not release immediately due to the fact that a charging current is drawn from battery B2 by the con denser C1. This current flows through the large resistance R2 and the winding TV3 of the relay and keeps the relay operated until the condenser has become sutliciently charged. After the charging current has fallen sufficiently in `value so that its inagneticeifect upon the armature of the relay is less than that of the biasing current in winding Wi, the line relay will release and remove the short-circuit from the east-to-west line. If the speaker resumes talking,the above operation 'will be repeated.

The Yhang-over time of relay 2 depends upon the values of R2, C1 and the biasing current in V4. The time can be changed by changing either one of these values but in practice it will probably be desirable to change either R2 or C1. Itshould be evident that the hang-over time can be kept fairly constant, since R2 and C will remain constant and there will be very little change in the biasing current of the relay due to normal variations in the voltage of battery BL. This also applies to neutral relays, although to a less extent, due to possible variations in spring tension.

During actual operating conditions on a circuit, the control relay l will follow the iiuctuations of the voice current quite faithfully, while the line relay 2 will remain on Vits M Contact. This is due to the fact that the condenser C1 will be charged and discharged rapidly by the operation of the control relay, so that an operating current will keep iiowing through the winding N3 of the line relay.

VThe latter relay will, therefore, remain operated and vwill release only in case the control relay remains on its S contact for an interval of time longer than the hang-over time .of relay 2.

For certain voice-operated devices it is desirable that the full hang-over time of the line relay should occur only if the control relay remains operated for an appreciable length of time. This is to prevent short induced clicks due to switching impulses on the same or on adjacent circuits from locking up the devices for the full hangover period. The proposed arrangement can be made to take care of this feature by making the resista-nce 'El large so that the condenser C1 will become only partially discharged during the time of such clicks. Consequently the 4hang-over time will be decreased because the initial charging current ill be lower in magnitude. The operation of the second half of the echo suppressor shown on the sketch is identical with thatdescribed above. In this case loperation of the relays occurs for voice currents transmitted from east to west through the amplifierv A2. The variousjelements -in the second half of the echo suppressor are identical with those in the first half and like elements are designated with the same letters, but with the addition of a prime.

`While the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable, it is understood that it is capable of embodiment in many'and other widely varied forms without departing from the spirit of the invention as defined in the appended claims.

l/Vhat is claimed is: 1. A transmission line over whichsignaling currents are transmitted, a control relay and a line relay having operating windings connected in a common initial energizing circuit, means in said. circuit common to both windings to determine Vthe energization of said operating windingsunder the control of signaling currents transmitted ,over said line, a condenser, a charging circuit for said condenser including a winding of said line relay but not a winding of said control relay, and switching means controlled by said control relay for discharging said condenser, said switching means being ineffective to pro- -duce initial energization of the winding of said line relay.

2. A transmission line overkwhich signaling ycurrents are transmitted, acontrol relay and a line relay having operating windings connected in a common initial energizing circuit, means in said circuit common to both windings Yto determine the energization of said operating Vwindings vunder the control of signaling currents transmitted over saidline,

and a slow electrical circuit controlled by said control relay and connected to a winding of said line relay to retard the release of said line relay, without being effectively connected to said control relay, and said control relay being ineffective to produce initial energization of said line relay.

3. A transmission line over which voice currents. are transmitted, a .control relay and 130 a line relay having operating windings connected 1n a common 1n1t1al energizing circuit, means in said circuit common to both windings to determine the energization of said operating windings under the control of signaling currents transmitted over said line, a condenser, a charging circuit for said condenser including a winding of said line relay but not a winding of said control relay, a resistance in said charging circuit to limit the rate of charging, a discharge circuit for said condenser controlled by said control relay, and a resistance in said discharge circuit to limit the rate of discharging, said control relay being ineffective to produce initial energization of said line relay.

4. A transmission line over which voice currents are transmitted, a control relay and a line relay having operating windings connected in a common initial energizing circuit, means in said circuit common to both windings to determine the energization of said operating windings under the control of signaling currents transmitted over said line, a condenser, a charging circuit for said condenser including a winding of said line relay but not a winding of said control relay and a resistance to limit the rate of charging, a discharge circuit for said condenser controlled by said control relay, said control relay being ineifective to produce initial energization of said line relay, and a resistance for so adjusting the characteristics of said discharge circuit that substantially full discharge will occur only if the control relay remains operated longer` than a definite length of time.

5. A transmission line over which voice currents are transmitted, a control relay and a line relay having operating windings connected in a common initial energizing circuit,

means in said circuit common to both windings to determine the energization of said operating windings under the control of signaling currents transmitted over said line, a condenser, a charging circuit for said condenser including a winding of said line relay but not a winding of said control relay and a resistance to limit the rate of charging, a discharge circuit for said condenser controlled by said control relay said control relay being ineective to produce initial energization of said line relay, and a resista-nce in said discharge circuit adjusted to limit the rate of discharge so that substantially full discharge of the condenser and therefore the full line relay hang-over period will be obtained only if the control relay remains operated longer than a definite length of time, and a partial hangover period will be obtained if the control relay remains operated for a period of time less than said definte length of time.

6. A transmission line over which voice currents are transmitted, a control relay and a line relay having operating windings connected in a common initial energizing circuit, means in said circuit common to both windings to determine the energization of said operating windings under the control of signaling currents transmitted over said line, a condenser, a charging circuit for said condenser including a .winding of said line relay but not a winding of said control relay, a resistance in said charging circuit to limit the rate of charging, a discharge circuit for said condenser controlled by said control relay, said control relay being ineffective to produce initial energization of said` line relay, and a resistance in said discharge circuit adjusted to limit the rate of discharge so that substantially full discharge and consequently the full line relay hang-over period will be obtained only if the control relay remains operated longer than a definite length of time, and a partial hang-over period will be obtained if the control relay remains operatedfor a period of time less than said definite length of time, the length of said partial hang-over period being a function of the period of time during which the control relay remains operated.

7. A transmission line over which signaling currents are transmitted, a control relay and a line relay having operating windings connected in a common initial energizing circuit, means `in said circuit common to both windings under the control of signaling currents transmitted over said line, a slow electrical circuit controlled by said control relay and connected to a winding of said line relay to retard the release of said line relay without being effectively connected to said control relay, and said control relay being ineective to produce initial energization of said line relay, and means associated with said slow electric circuit for varying the retarding effect thereof.

8. In an echo suppressor device operating between the sides of a four-wire system, the method of retarding by a relay operatively connected to one side of said system the release of a secondy relay also operatively connected to the same side of said system and operating for disabling the other side of the system, which consists of initially discharging a condenser associated with a winding of the second mentioned relay by the operation ofthe first mentioned relay, and permitting the charging current of said condenser to retard the release of the second mentioned relay upon the release of the first mentioned relay.

In testimony whereof, I have signed my name to this specification this 27th day of October, 1926.

JOSEPH HERMAN. 

